<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>元素重叠</title>
    <style>
        img
        {
            position: absolute;
            left: 0px;
            top: 0px;
            z-index: -1;
        }
    </style>
</head>
<body>
<h1>
    This is Head and Topic.
</h1>
<img src="css/img/bcd.jpg" width="1000" height="600"/>
</body>
</html>